1. Field of the Invention
The present invention relates to a charge control device for a battery used for cycle use.
2. Description of the Related Art
A conventional technique for controlling charge to a lead battery, which is used for an electric car or the like, is the charge method of JP 2006-114312. The method of JP 2006-114312 employs a constant current multi-stage charge system, and multiple stage charge steps (charge stages) are executed one after another in one charge operation revolution. A charge current amount charged into the lead battery is decided every charge step and is set to be lower as the charge step proceeds to the later stage. At each charge step, the battery is charged based upon a previously allotted charge current amount. The charge step is changed to another charge step of the next stage when a battery voltage reaches a preset voltage Vr.
On this occasion, at the initial charge step, a charge time of the final step is decided based upon a charge electricity quantity and a battery temperature at the particular step. Thus, at the final step, the charge is completed when the charge time elapses.
However, if the charge method described above is employed, a situation may occur where the charge step cannot be changed to the next charge step even when a long time elapses due to some deterioration condition of the battery. That is, because the condition is set in such a manner that the charge step is changed to the next step when the battery voltage reaches the preset voltage Vr, the battery voltage hardly reaches the preset voltage Vr that is the step change determining condition, particularly, at the later step(s) where the charge is executed with the charge current value being lower, if the battery has deteriorated. As a result, the battery is overcharged and the life of the battery can be shortened.